[R-390] 390() vs 390(A)

[Roy Morgan]

At 01:46 PM 12/27/2004, Paul H. Anderson wrote:
>Don't forget the R-389,
>
>The VFO and RF decks of the R-389 are very different,

An understatement!

>and there is a
>rectifier stack for producing DC for the R-389 tuning motor.  Oddly, the
>R-391, which also has a DC motor for tuning, doesn't have the rectifier
>stack.  There probably wasn't room, if I had to guess.

The auto tuning motors in the R-391 take MUCH more current than the tuning 
motor in the R-389.  In the R-391, both the KC and MC setting mechanisms 
are moved by (separate) Motors and associated position setting 
mechanisms.  The DC supply for that is external to the radio, and if I 
remember correctly, is about the same size as the radio itself.  In the 
R-389, only the single tuning knob is moved, so the mechanical work (torque 
times rotations per minute) is much less.  There is no presetting of 
frequencies in the R-389.  The motor is there to assist the operator in 
moving the many many turns (up to 50) from one spot in the frequency range 
to another.

Roy

- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
7130 Panorama Drive, Derwood MD 20855
Home: 301-330-8828 Cell 301-928-7794
Work: Voice: 301-975-3254,  Fax: 301-948-6213
roy.morgan at nist.gov --